Remove post processing core

[mo-marqh]

PR Summary

Sci/Tech Reviewer:
Code Reviewer: Steve Mullerworth (@stevemullerworth)

This change removes the post-processing logic for the majority of cases from core

• This logic is not compatible with XIOS3.
• This logic is not well engineered with regard to MPI, init_wait calls.
• This logic is not well optimised for file storage access at scale.
• lfric_apps metadata definitions have meant that the use of the code is sporadic and not well understood with regard to triggers within lfric_apps

In detail:

1. the definition of global attributes is replaced by direct XIOS usage.
2. the definition of time metadata, including forecast_reference_time is removed;
   • this will be provided in a separate PR, due to implementation complications with lfric_apps
     • (see reducing post-processing of XIOS output #204 & File metadata and Forecast reference Time Scalar to reduce post processing from lfric core lfric_apps#90 for details)
3. the definition of scaling for UGRID planar coordinates is retained
   • to support specific test cases, that are not used in suites and large scale simulations
   • that are protected by careful logic to only run in these cases

• intended to replace reducing post-processing of XIOS output #204

Code Quality Checklist

• I have performed a self-review of my own code
• My code follows the project's style guidelines
• Comments have been included that aid understanding and enhance the readability of the code
• My changes generate no new warnings
• All automated checks in the CI pipeline have completed successfully

Testing

• I have tested this change locally, using the LFRic Core rose-stem suite
• If required (e.g. API changes) I have also run the LFRic Apps test suite using this branch
• If any tests fail (rose-stem or CI) the reason is understood and acceptable (e.g. kgo changes)
• I have added tests to cover new functionality as appropriate (e.g. system tests, unit tests, etc.)
• Any new tests have been assigned an appropriate amount of compute resource and have been allocated to an appropriate testing group (i.e. the developer tests are for jobs which use a small amount of compute resource and complete in a matter of minutes)

trac.log

Test Suite Results - lfric_core - remove-post-processing-core/run2

Suite Information

Item	Value
Suite Name	remove-post-processing-core/run2
Suite User	mark.hedley
Workflow Start	2026-05-14T10:23:56
Groups Run	all

Dependency	Reference	Main Like
lfric_core	mo-marqh/lfric_core@remove-post-processing-core	False
SimSys_Scripts	MetOffice/SimSys_Scripts@cab3315	True

Task Information

✅ succeeded tasks - 402

also tested with lfric_apps main to confirm compatibility

Test Suite Results - lfric_apps - test_apps_remove-post-processing-core/run1

Suite Information

Item	Value
Suite Name	test_apps_remove-post-processing-core/run1
Suite User	mark.hedley
Workflow Start	2026-05-14T10:32:11
Groups Run	all

Dependency	Reference	Main Like
casim	MetOffice/casim@2026.03.2	True
jules	MetOffice/jules@2026.03.2	True
lfric_apps	mo-marqh/lfric_apps@7f8f805	True
lfric_core	mo-marqh/lfric_core@dec84ae	True
moci	MetOffice/moci@2026.03.2	True
SimSys_Scripts	MetOffice/SimSys_Scripts@cab3315	True
socrates	MetOffice/socrates@2026.03.2	True
socrates-spectral	MetOffice/socrates-spectral@2026.03.2	True
ukca	MetOffice/ukca@1cdb9c2	True

Task Information

❌ failed tasks - 4

Task	State
rose_ana_lfricinputs_um2lfric-aquaplanet_lbc_azspice_gnu_fast-debug-64bit	failed
rose_ana_lfricinputs_um2lfric-aquaplanet_lbc_azspice_gnu_full-debug-64bit	failed
rose_ana_lfricinputs_um2lfric-aquaplanet_lbc_ex1a_gnu_fast-debug-64bit	failed
rose_ana_lfricinputs_um2lfric-aquaplanet_lbc_ex1a_gnu_full-debug-64bit	failed

✅ succeeded tasks - 1538

⌛ waiting tasks - 2

Task	State
housekeep_azspice	waiting
housekeep_ex1a	waiting

Security Considerations

• I have reviewed my changes for potential security issues
• Sensitive data is properly handled (if applicable)
• Authentication and authorisation are properly implemented (if applicable)

Performance Impact

• Performance of the code has been considered and, if applicable, suitable performance measurements have been conducted

AI Assistance and Attribution

• Some of the content of this change has been produced with the assistance of Generative AI tool name (e.g., Met Office Github Copilot Enterprise, Github Copilot Personal, ChatGPT GPT-4, etc) and I have followed the Simulation Systems AI policy (including attribution labels)

Documentation

• Where appropriate I have updated documentation related to this change and confirmed that it builds correctly

PSyclone Approval

• If you have edited any PSyclone-related code (e.g. PSyKAl-lite, Kernel interface, optimisation scripts, LFRic data structure code) then please contact the TCD Team

Sci/Tech Review

• I understand this area of code and the changes being added
• The proposed changes correspond to the pull request description
• Documentation is sufficient (do documentation papers need updating)
• Sufficient testing has been completed

(Please alert the code reviewer via a tag when you have approved the SR)

Code Review

• All dependencies have been resolved
• Related Issues have been properly linked and addressed
• CLA compliance has been confirmed
• Code quality standards have been met
• Tests are adequate and have passed
• Documentation is complete and accurate
• Security considerations have been addressed
• Performance impact is acceptable

[mo-marqh]

there are 4 failing rose_ana tests in the lfric_apps test suite, where the diff from nccmp is highlighting the removal of forecast_reference_time and forecast_period

This is the expected change from this change Set.

It is not clear whether a linked PR is needed here, as the code and tests would not change to let these pass, instead the static files that support these rose_ana tests would need to be updated.
e.g.
/home/users/umadmin/standard_jobs/lfricinputs/kgo/lfricinputs_um2lfric-aquaplanet_lbc_azspice_gnu_fast-debug-64bit/vn3.1/checkpoint_um2lfric_000001.nc

this code is ready for Sci/Tech review, but this lfric_apps testing coordination needs addressing before it passes cove review.